The containment of hazardous materials, whether resulting from a spill of the materials, or from the burial of the materials in a landfill, is a matter of great concern. Toward this end, a great number of environmental laws have been enacted which require landowners to take affirmative steps to prevent the spread of pollutants and hazardous materials from migrating from the location of the material burial or storage site giving rise to a polluting or hazardous condition, and particularly with regard to the prevention of groundwater migration of the pollutants or hazardous materials as this can impact water quality in lakes and streams, as well as drinking water supplies in surrounding communities.
The use of both metallic and plastic sheet pilings to form retaining walls is well known. However, sheet piling is not well adapted for use in forming a fluid-tight containment barrier as most all sheet piling, by its nature, is intended to weep along the edge-standing joints of the adjacent ones of the sheet piling panels in order to prevent the buckling or failure of the retaining wall made out of such sheet piling due to groundwater build-up during rainy seasons, flood conditions, or ocean tides. Moreover, steel sheet piling is not well suited for use in forming an underground containment barrier for waste storage sites in that steel will eventually rust and corrode, allowing migration of groundwater therethrough. Even coated steel sheet piling may be subject to corrosion due to the inevitable scratching of the surface finish of the sheet piling as it is driven into the Earth, which ultimately leads to corrosion and/or the failure of the sheet piling used to construct the containment barrier wall.
Accordingly, the use of extruded plastic sheet piling for use in forming containment barriers has arisen, as plastic is much more resistant not only to corrosion, but also to the hazardous and/or toxic material being contained. One example of such a sheet piling is shown in U.S. Pat. No. 4,808,039 to Fischer which discloses a coupling mechanism for interconnecting sealing plates built into sealing walls, for example extruded plastic sheet piling, to be used as a containment barrier. In Fischer, however, a problem arises in the manner of sealing the sealing strip of the sealing plate to the mating portion of an adjacent sealing plate/sheet piling, especially after the sheet pilings have been driven in position about the waste burial or containment site, in that the sealing strip needs to be glued or hot welded to the mating portion which appears to be extremely difficult to accomplish, if not impossible, once the sheet pilings have been driven into the Earth.
U.S. Pat. No. 5,106,233 to Breaux discloses a hazardous waste containment system utilizing an extruded tubular sheet piling, which can be mated to adjacent ones of the sheet piling extrusion to form a wall about the waste burial site, whereupon a sealant, for example a silicon material, is injected into a seal receptor chamber formed by the mating of adjacent sheet pilings to one another in the effort to form a fluid-tight seal. Although this appears to be a workable approach to building a containment barrier wall about a waste burial site, the problem exists in that the seal receptor chamber into which the silicon, or other viscous sealant, is pumped could be obstructed by a rigid but porous rock, organic debris, or other material which would prevent the flow of the sealant along the length of the containment barrier, thus leaving holes within the barrier such that groundwater and gases could migrate into and out of the waste burial site.
Yet another barrier panel system is disclosed in U.S. Pat. No. 5,360,293 to Breaux, et al. which discloses an in-ground barrier member interlocking joint and seal system. Here, a joint/sealing system is provided for forming interlocked in-ground barrier members into an in-ground containment wall. The respective barriers, or barrier members each having a female member including a "U"-shaped gasket adapted to receive a longitudinally extending male member of a second barrier member, the gasket being fastened onto the female member into which the male members will be passed. Although this patent teaches a barrier member which overcomes the problem of injecting a sealant along the length of the barrier panels, the problem exists in that the gasket material must be somehow joined to the female end of the in-ground barrier member such that it will not be stripped out or otherwise damaged or destroyed while being driven into the Earth prior to receiving the male end of an adjacent in-ground barrier member such that a nonfluid-tight seal may result along a portion of the length of the joint between adjacent barrier members, again allowing groundwater and gases to migrate therethrough. Also, the material used to form the U-shaped gaskets is preferably a second material different than the plastic used to extrude the barrier members, which naturally increases material costs.
An alternate embodiment of Breaux, et al. discloses the co-extrusion of the gasket with the barrier member for an intermediate connecting piece having two female members along its opposed sides for receiving respective ones of the male members of adjacent barrier panels therein, thus requiring the use of two different types of barrier members to construct a containment barrier wall. Nothing is taught in Breaux, et al. as to whether the same material is to be used for extruding both the barrier member and the gaskets. It must be inferred, therefore, that a first plastic will be used to extrude the barrier member and a second elastomeric material used to extrude the gasket.
What is needed, but seemingly unavailable in the art, therefore, is a one-piece containment barrier panel extrusion which can be quickly and easily used to form a fluid-tight containment barrier wall about a defined geographic area, for example a landfill or a hazardous waste material burial site, which ensures that a fluid-tight seal is formed about the geographic area so that groundwater, surface water, or underground gases, for example methane, cannot migrate out of the waste material site. What is also required is such an improved containment barrier panel which does not require that a separate sealant be injected into a space defined between adjacent ones of the barrier panels after having been driven into the Earth about the waste material burial site, and/or which will not require that a gasket material, or other type of hydrophilic sealing material be applied or adhered to at least one side of such a barrier panel for forming a fluid-tight seal. Also, the need exists for such an improved containment barrier panel which can be used to form a containment barrier wall without requiring the use of differing designs of containment barrier panels such that a single type or design of the containment barrier panel can be used to construct the containment barrier wall about a hazardous waste material storage or burial site.